Hand dryer having managed air flow

ABSTRACT

A method and apparatus for drying objects in low-volume enclosed spaces is disclosed. In one embodiment, the apparatus is a hand dryer that comprises a dryer cavity including an input port, an exhaust port, and an opening for insertion of a hand having moisture thereon, an air channel, pneumatically coupling the exhaust port of the dryer cavity to the input port of the dryer cavity, the air channel substantially isolated from an interior volume of the lavatory, and a blower, communicatively coupled to the air channel, for moving air through the air channel and the dryer cavity.

BACKGROUND 1. Field

The present disclosure relates to systems and methods for drying hands,and in particular to a system and method for drying hands in an enclosedenvironment.

2. Description of the Related Art

For many years, aircraft have been fitted with aircraft lavatories, foruse by passengers and crew. Such lavatories include a washbasin andfaucet to allow users to wash their hands, and offer paper towels forpurposes of drying their hands after washing.

While effective, drying hands with paper towels has a number ofdisadvantages. First, the supply of paper towels in each lavatory mustbe periodically checked and replenished. Second, paper towels must bediscarded after use. Although lavatories are equipped with a vessel fordisposing of paper towels, it is not unusual for paper towels to bedropped in the lavatory itself instead of the vessel. Further, suchvessels are typically covered by a spring loaded door, requiring theuser to physically touch the door to urge it forward to place the papertowel in the vessel. This presents an opportunity to spread germs to thedoor, and hence to other passengers. Third, paper towels must be removedfrom the vessels in the lavatory on a frequent basis and disposed of ina location other than the aircraft. Finally, once removed from theaircraft, the waste generated by paper towels must be recycled orotherwise disposed of.

These problems have led to the use of air-driven hand dryers instead ofpaper towels for many applications. For example, the “Sterilizing HandDryer” disclosed in U.S. Pat. No. 3,766,397 (hereby incorporated byreference herein) draws air from the room in which it is installed viaport (23) and exhausts the moisturized air through a second port (29).This allows the exhausted air to increase the temperature of the room inwhich the hand dryer is installed, and renders it ineffective for use ina small enclosed volume and or recirculating ventilation such as anaircraft lavatory. U.S. Patent Application 2015/0210398 (also herebyincorporated by reference herein) discloses integrating a lavatory andgalley ventilation system (LGVS) of an aircraft with the environmentalcontrol system of an aircraft to facilitate movement of waste air, butdoes not address the additional and significant load placed on suchsystems when hand dryers are used.

There is an on-going need in the art for air-driven hand dryers thataddress shortcomings of conventional designs.

SUMMARY

This document discloses a system and method for drying hands or otherobjects in a lavatory of an aircraft. In one embodiment, the systemcomprises a dryer cavity including an input port, an exhaust port, andan opening for insertion of a hand having moisture thereon, an airchannel, pneumatically coupling the exhaust port of the dryer cavity tothe input port of the dryer cavity, the air channel substantiallyisolated from an interior volume of the lavatory, and a blower,communicatively coupled to the air channel, for moving air through theair channel and the dryer cavity. Another embodiment is evidenced by amethod of drying a hand in a lavatory of an aircraft, which comprisesaccepting a hand having moisture thereon in an opening of a dryer cavityhaving an input port and an exhaust port, blowing air through the dryercavity via the input port, the blown air removing at least some of themoisture from the hand accepted into the opening of the cavity, andexhausting substantially all of the blown air from the dryer cavityexternal to the lavatory through the exhaust port. Still anotherembodiment is evidenced by a means for performing the foregoingoperations.

Conventional air-driven hand dryers have particular disadvantages whenused in aircraft, small vehicles, or other applications where involvingclosed spaces. In particular, (1) use of a air-driven hand dryer itfurther lowers the humidity in the aircraft cabin; (2) the amount of airfrom the dryer relative to the volume of space in the lavatory(typically less than, e.g., 75 cubic feet) cause the temperature in thelavatory to be elevated during high-use periods, making the lavatoryuncomfortable, and promoting bacteria growth; (3) the air blown from thedryer will also blow the water off of the user's hands onto the floor orsurrounding surfaces. The embodiments described in this disclosureaddress and overcome these disadvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings in which like reference numbers representcorresponding parts throughout:

FIGS. 1A and 1B are diagrams presenting respective top and side views ofa typical aircraft lavatory;

FIG. 2A is a diagram of one embodiment of a hand dryer for use in anaircraft lavatory;

FIG. 2B is a diagram of another embodiment of the hand dryer;

FIG. 3 presents a functional block diagram of one embodiment of the handdryer;

FIGS. 4A and 4B are diagrams illustrating another exemplary embodimentof the hand dryer;

FIGS. 5A and 5B are diagrams illustrating one embodiment of aninstallation of the hand dryer in an aircraft lavatory;

FIGS. 6A and 6B are diagrams illustrating another embodiment of theinstallation of the hand dryer in the aircraft lavatory; and

FIG. 7 is a diagram illustrating exemplary operations that can beperformed to drying one or more of a user's hands in a lavatory of theaircraft.

DESCRIPTION

In the following description, reference is made to the accompanyingdrawings which form a part hereof, and which is shown, by way ofillustration, several embodiments. It is understood that otherembodiments may be utilized and structural changes may be made withoutdeparting from the scope of the present disclosure.

Overview

A hand dryer with managed air flow is described below. The hand dryerdirects air into a hand drying cavity, into which the user inserts theirhands. Moisture blown or evaporated from the user's hands is collectedat an exhaust port of the cavity and removed from the lavatory. Thisprevents moisture and humidity from escaping the hand dryer, thusreducing the spread of microbes while also minimizing the impact of theblown air upon the humidity and temperature of the lavatory and theaircraft cabin. The hand dryer has a number of optional features,including an automatic engagement feature, which turns the hand dryer onwhen the user inserts their hands into the cavity, an antimicrobialsource (such as a ultraviolet (UV) light emitter) to assist in thesanitation of the user's hands, the use of a second fan to affirmativelyvacuum moisture laden air from the cavity, and the use of inert air asthe source of positive air flow.

In one embodiment, the cavity includes inlet to provide air to thecavity and an exhaust air duct to channel the air back to the dryer tobe recycled. Alternatively, the exhaust duct may feed the air to someother air management system [e.g., the environmental control system(ECS) of the aircraft]. Another feature of the hand dryer is a watermanagement device for containing water blown off of the hands by thedryer so that the blown water does not end up on the floor of thelavatory or on surfaces in the lavatory.

FIGS. 1A and 1B are diagrams presenting respective top and side views ofan enclosed lavatory 100 such as an aircraft lavatory. The lavatory 100includes a lavatory interior volume 102 enclosed by lavatory walls 103,a counter 105, and other interior surface of the lavatory 100. Thelavatory 100 also includes one or more doors 104 which permit access tothe lavatory 100. Doors 104 are typically are compact folding doors.

The lavatory may also comprise a toilet 106 and a water faucet 110having a proximally disposed washbasin 108 for washing the user's hands.Typically, such lavatories 100 also include a toilet paper dispenser 118and/or a paper towel dispenser 112. The paper towel dispenser 112dispenses paper towels for the purpose of drying the user's hands. Afteruse, the paper towels can be inserted into paper towel disposingaperture 114, which allows the paper towel to drop into a disposalvessel 116. As described above, the paper towel dispenser 112 must beperiodically replenished with paper towels, and the disposal vessel 116must be emptied of used paper towels.

FIG. 2A is a diagram of one embodiment of a hand dryer 200 for use in anaircraft lavatory 100. The hand dryer 200 comprises a dryer cavity 228having an input port 204, an exhaust port 206, and an opening 230 forthe insertion of one or more hands having moisture thereon. The handdryer 200 also comprises an air channel 210 that pneumatically couplesthe exhaust port 206 of the dryer cavity 228 with the input port 204 ofthe cavity 228. The air channel 210 is substantially pneumaticallyisolated from the interior volume 102 of the lavatory 100, and is atleast partially comprised of ducting 205. The vertically orientedconfiguration of the ducting 205 is shown for illustrative purposesonly, as the ducting 205 may be routed in any direction necessary toinstall the hand dryer 200 in the desired location in the lavatory. Thehand dryer 200 also comprises or is connected directly or indirectly toa blower 214 pneumatically communicatively coupled to the air channel210, for moving air through the air channel 210 and the dryer cavity228. The blower 214 may exit in different part of the vehicle such as anair circulation engine in an airplane. It can blow air out or in.

In the illustrated embodiment, the hand dryer comprises a substantiallyclosed-circuit air path 212 in which the exhaust port 206 of the dryercavity 228 is pneumatically sealingly coupled to the input port 204 ofthe dryer cavity 228. In one embodiment, the closed circuit air path 212include elements that assist in the drying and cooling (if necessary) ofthe air as it is passed through the air channel 210. Such elements caninclude, for example, baffling or heat sinks.

FIG. 2B is a diagram of another embodiment of the hand dryer 200. Inthis embodiment, the aircraft comprise an environmental control system(ECS) 250. The ECS 250 includes air intakes to accept air from theaircraft cabin and air vents to vent air into the aircraft cabin, andmaintains a desired temperature, humidity, and atmospheric pressure inthe aircraft cabin. In the embodiment illustrated in FIG. 2B, the airchannel 210 pneumatically couples the exhaust port 206 of the dryercavity 228 to the input port 204 of the dryer cavity 228 via the ECS250. This is accomplished by configuring the hand dryer 200 such thatthe input port 204 of the dryer cavity 228 is pneumatically coupled toan ECS air source port 254 and the exhaust port 206 of the dryer cavity228 is pneumatically coupled to the ECS air exhaust port 252.Consequently, the air passing through the cavity 228, and into the dryercavity exhaust port 206 [which has become humidified (and optionallyheated) is provided to the ECS 250] and does not enter the interiorvolume 102 of the lavatory 100. Instead, this air is provided to the ECS250 where it may be dehumidified and cooled before being provided to theinput port 204 of the dryer cavity 228.

In one embodiment, the dryer cavity 228 is substantially enclosed aroundthe opening 230 (in which the user's hands are inserted) so that airmoved by the blower 214 through the dryer cavity 228 is substantiallyexhausted from the dryer cavity 228 via the exhaust port 206 (and notthe opening 230).

In the illustrated embodiment, the blower 214 is disposed proximate (andupstream of) the input port 204 of the dryer cavity 228, and alsoincludes an optional second blower 220 disposed proximate (anddownstream of) the exhaust port 206. This second blower 220 assists inthe drawing of air from the dryer cavity 228 by creating a vacuum in thevicinity of the exhaust port 206. In one embodiment, the vacuum createdis sufficient to draw virtually all of the air blown into the dryercavity 228 by the blower 214 through the exhaust port 206 and into theair channel 210. In another embodiment, the vacuum created by the secondblower 220 is sufficient to draw additional ambient air from theinterior volume 102 of the lavatory 100, thus assuring that none orvirtually none of the air blown into the dryer cavity 228 by blower 214escapes the dryer cavity 228 and enters the interior volume 102 of thelavatory 100. Although the input port 204 and the exhaust port 206 areillustrated as being of the same dimension, this need not be the case.The input port 204 may be smaller than illustrated to create a venturieffect to increase the speed of the air blown into the cavity 228, andthe exhaust port 206 may be larger than illustrated to draw more airfrom the cavity 228. Likewise, blowers 214 and 220 may be of differentsizes, or use different configurations. For example, while blowers 214and 220 both show the use of a propeller to urge air therethrough,different impeller configurations can be used, including that ofsquirrel cage-type impellers. Furthermore, compressed air, blown intothe area proximate the exhaust port 206 may be used to create thedesired vacuum.

FIGS. 2A and 2B also illustrate a moisture containment device 222, totrap moister dripping or otherwise removed from the user's hands andprevent this moisture from going deeper into the air channel 210. Themoisture containment device 222 may comprise one or more substantiallypneumatically transparent screens, which may optionally be heated so asto evaporate any liquid moisture to gaseous form, where it can beremoved, either in the closed circuit or ECS configuration of FIGS. 2Aand 2B, respectively. In the illustrated embodiment, the moisturecontainment device 222 is disposed upstream from the second blower 220,but the moisture containment device 222 may instead be disposeddownstream from the second blower 220.

FIGS. 2A and 2B disclose other optional hand dryer 200 features as well.For example, the hand dryer 200 may comprise a hand sanitizer 216 thatdirects an antimicrobial substantially into the user's hands wheninserted in the dryer cavity 228. In one embodiment, the hand sanitizer216 comprises a source of ultraviolet (UV) light, such as a far field UVemitter, far-UV emitting diode (LED), OLED, or germicidal UV source. Inthis embodiment, the UV LED is configured to direct energy substantiallyonly within the dryer cavity 228, and the dryer cavity may optionally beconfigured to include one or more surfaces configured to substantiallyconfine the UV light within the drying cavity 228. While all UV lightmay not be confined to within the drying cavity 228, the dryer cavityconfiguration is such that the amount and direction of the UV light thatescapes from the dryer cavity is not harmful to humans in dosesanticipated by the most frequent users of the lavatory. In theillustrated embodiment, such surfaces include a UV absorbing surface 218or baffling surface 226. In another embodiment, the hand sanitizer 216comprises a device that sprays a liquid or gaseous antimicrobial withinthe drying cavity 228.

FIGS. 2A and 2B also disclose another optional feature of the hand dryer200, namely, an automatic activation device. The automatic activationdevice comprises a sensor 224 that transmits a signal to activate thehand dryer 200, turning on the blower(s), any heating elements, andother components when the it senses that the one or more of the user'shands have been inserted into the cavity 228. In one embodiment, theautomatic activation device comprises a proximity sensor 224, thatsenses the proximity of the user's hands to the sensor. The proximitysensor 224 may be passive (e.g. sense energy emitted by the usershands), active (e.g. sense energy emitted by the proximity sensor 224and reflected by the user's hands), or semi-active (e.g. sense energyprovided by other sources such as lavatory 100 illumination). Theproximity sensor 224 may also be a threshold crossing sensor thattransmits an energy beam across the opening 230 and that includes areceiver to receive that energy beam and to detect when that energy beamis interrupted (thus indicating the insertion of an energy beam-opaqueobject into the opening 230). If an automatic activation device is notprovided, the hand dryer 200 may be activated by a switch.

FIGS. 2A and 2B also illustrate another optional feature of the handdryer 200, namely, a pneumatically transparent heater 232. Since heatedair can dry hands faster than air of ambient temperature, the use ofheater 232 to heat the air drawn from the air channel 210 and blown intothe dryer cavity 228 can provide faster dry times.

FIG. 3 presents a functional block diagram of one embodiment of the handdryer 200. The hand dryer 200 comprises a controller 302 communicativelycoupled to the sensor 224 to accept the signal indicating that theuser's hand(s) have been inserted into the dryer cavity 228. Thecontroller 302 then sends a signal or power (or both) to activate thecommunicatively coupled blower motor(s) 214, 220, heater(s) 232, 222,and antimicrobial source 216, or any combination thereof according tothe specific implementation. The controller also may monitor anycombination of the temperature, humidity, and air flow within the dryercavity 228 to assure proper operation, and if improper operation issensed, shut off the hand dryer 200. This may occur, for example, if anobject is inserted into the dryer cavity 228 and left there for anextended period of time.

In one embodiment, the controller 302 comprises a processor 304 and acommunicatively coupled memory 306 storing processing instructions forperforming the operations of the controller 302. The processor 304 maybe communicatively coupled to other aircraft subsystems, including theECS 250 so that the operation of the hand dryer 200 may be monitored orremotely controlled.

FIGS. 4A and 4B are diagrams illustrating another exemplary embodimentof the hand dryer 200. In the embodiments shown in FIGS. 2A and 2B, thehand dryer is vertically oriented. That is, the input port 204 and theexhaust port 206 are disposed on vertically opposing sides of the dryercavity 228. FIGS. 4A and 4B illustrate an exemplary embodiment of thehand dryer 200 in which the input port 204 and the exhaust port 206 aredisposed on horizontally opposing sides of the dryer cavity 100. Anillustrative embodiment if this configuration of the hand dryer 200 isfurther illustrated below. One particular advantage of this embodiment,is that it prevents dripping water from the user's hands from enteringthe exhaust port 222 and can be conveniently mounted proximate to thewashbasin 108.

FIGS. 5A and 5B are diagrams illustrating one embodiment of aninstallation of the hand dryer 200 in an aircraft lavatory 100. In thisembodiment, the hand dryer 200 is configured as illustrated in FIG. 2Aor 2B and is installed in a vertical surface of the lavatory 100, forexample, within the counter 105 as illustrated, with the ducting 205routed as necessary. The hand dryer 200 may be installed in any otherwall in the lavatory 100 as well, again with ducting 205 routing asneeded.

FIGS. 6A and 6B are diagrams illustrating another embodiment of theinstallation of the hand dryer 200 in the aircraft lavatory 100. In thisembodiment, the hand dryer 200 is configured as illustrated in FIGS. 4Aand 4B and is installed in a horizontal surface of the lavatory 100, forexample, on the upper surface of the counter 105 as illustrated, withthe ducting 205 routed as necessary. The hand dryer 200 may also bemounted to alternative horizontal surfaces of the lavatory 100.

FIG. 7 is a diagram illustrating exemplary operations that can beperformed to drying one or more of a user's hands in a lavatory 100 ofan aircraft. In block 702, at least one of the user's hands is receivedor accommodated into an opening 230 of a dryer cavity 228 having aninput port 204 and an exhaust port 206. In block 704, air is blownthrough the dryer cavity 238 via the input port 204, and the blown airremoves at least some of the moisture from the hand accepted into theopening 230 of the cavity 228. In block 706, substantially all of theair blown into the dryer cavity 228 via the input port 204 is exhaustedexternal to the lavatory 100 through the exhaust port 206.

The foregoing operations may be practiced in a number of embodiments,the features of which may be used in different combinations as desired.

In one such exemplary embodiment, the air is blown through the dryercavity using a blower 214 which may comprise an electric motor and fanassembly. In a further related embodiment, air exhausted from the dryercavity 228 is air that is drawn from the dryer cavity 228 by a secondblower 220 disposed proximate the exhaust port 206.

The blown air that is removed from the dryer cavity 228 may be providedto the input port in a number of different ways. In an exemplaryembodiment, the blown air exhausted from the dryer cavity 228 throughthe exhaust port 206 is provided or recirculated back to the input port204 via a closed circuit air path 212. In another related embodiment,the air blown through the dryer cavity 228 via the input port 204 is airthat has been accepted from an ECS 250 of the aircraft, and the airexhausted from the dryer cavity 228 via the exhaust port 206 isexhausted to the ECS 250.

In still other embodiments, an antimicrobial is directed substantiallyinto the drying cavity 228 to assist in sanitizing the user's handsduring the hand drying process. This antimicrobial may comprise UV lightor a chemical antimicrobial. Further, a moisture containment device 222proximate the exhaust port may be used to remove moisture from theexhausted blown air.

Those skilled in the art will recognize many modifications may be madeto this configuration without departing from the scope of the presentdisclosure. For example, those skilled in the art will recognize thatany combination of the above components, or any number of differentcomponents, peripherals, and other devices, may be used. For example,although the foregoing embodiments depict a dryer cavity having an inputport pneumatically coupled to either closed circuit air channel, airthat is provided to the blower 214 and blown into the cavity 228 may beobtained from the ambient air in the interior volume 102 of the lavatory100. The air passing through the exhaust port 206 may be provided to theECS 250 for conditioning, and simply provided to the aircraft cabin orto a vent in the lavatory 100 itself. Further, although described asbeing used to dry hands in an aircraft lavatory, the foregoingprinciples are also applicable for other applications, for example, inthe drying of other objects, and in different locations where reducingthe effect of the drying process on small enclosed volumes is desired.

CONCLUSION

This concludes the description of a number of embodiments of the presentdisclosure. The foregoing description of the embodiments has beenpresented for the purposes of illustration and description. It is notintended to be exhaustive or to limit the disclosure to the precise formdisclosed. Many modifications and variations are possible in light ofthe above teaching, including modifications for other confined-space orlow-volume lavatories such as on trains, ships, buses, and so on. It isintended that the scope of rights be limited not by this detaileddescription, but rather by the claims appended hereto.

What is claimed is:
 1. A hand dryer for use in a lavatory of an enclosedvehicle, comprising: a dryer cavity including an input port, an exhaustport, and an opening for insertion of a hand having moisture thereon; anair channel, pneumatically coupling the exhaust port of the dryer cavityto the input port of the dryer cavity, the air channel isolated from aninterior volume of the lavatory; and a blower, communicatively coupledto the air channel, for moving air through the air channel and the dryercavity.
 2. The hand dryer of claim 1, wherein: the air channel comprisesa closed-circuit air path, pneumatically sealingly coupling the exhaustport of the dryer cavity to the input port of the dryer cavity.
 3. Thehand dryer of claim 1, wherein: the enclosed vehicle comprises anenvironmental control system (ECS); and the air channel pneumaticallycouples the exhaust port of the dryer cavity to the input port of thedryer cavity via the ECS.
 4. The hand dryer of claim 3, wherein: the ECSincludes an ECS air source port and an ECS air exhaust port; and theinput port of the dryer cavity is pneumatically coupled to the ECS airsource port and the exhaust port of the dryer cavity pneumaticallycoupled to the ECS air exhaust port.
 5. The hand dryer of claim 1,wherein the dryer cavity is substantially enclosed around the openingsuch that the air moved by the blower through the dryer cavity issubstantially exhausted from the dryer cavity via the exhaust port. 6.The hand dryer of claim 1, further comprising: a hand sanitizer, fordirecting an antimicrobial substantially into the drying cavity.
 7. Thehand dryer of claim 6, wherein: the hand sanitizer comprises a source ofultraviolet light, directing the ultraviolet light substantially onlywithin the drying cavity; and the drying cavity comprises at least onesurface configured to substantially confine the ultraviolet light towithin the drying cavity.
 8. The hand dryer of claim 1, wherein theinput port and exhaust port are disposed on opposing sides of the dryercavity.
 9. The hand dryer of claim 1, wherein the input port and exhaustport are disposed on horizontally opposing sides of the dryer cavity.10. The hand dryer of claim 1, wherein: the blower is disposed proximatethe input port of the dryer cavity; and the hand dryer further comprisesa second blower disposed proximate the exhaust port of the dryer cavity,for drawing the air from the dryer cavity and away from the lavatory.11. The hand dryer of claim 1, further comprising a moisture containmentdevice disposed proximate the exhaust port.
 12. The hand dryer of claim1, further comprising: a moisture containment device comprising apneumatically transparent screen, for removing moisture from the airdrawn from the dryer cavity; a second blower, disposed downstream fromthe pneumatically transparent screen, for drawing the air from the dryercavity and through the pneumatically transparent screen.
 13. A lavatoryof an aircraft, comprising the hand dryer of claim
 1. 14. An aircraft,comprising the lavatory of claim
 13. 15. A method of drying a hand in alavatory, comprising: receiving the hand having moisture thereon in anopening of a dryer cavity having an input port and an exhaust port;blowing air through the dryer cavity via the input port, the blown airremoving at least some of the moisture from the hand accepted into theopening of the cavity; exhausting the blown air from the dryer cavityexternal to the lavatory through the exhaust port; and providing theblown air from the exhaust port to the input port of the dryer cavityvia an air channel isolated from an interior volume of the lavatory. 16.The method of claim 15, wherein providing the blown air from the exhaustport to the input port of the dryer cavity via the air channel isolatedfrom the interior volume of the lavatory comprises providing the blownair from the exhaust port to the input port of the dryer cavity via aclosed-circuit air path.
 17. The method of claim 16, wherein: blowingair through the dryer cavity via the input port comprises: accepting airfrom an environmental control system (ECS) of an aircraft; and blowingthe accepted air through the dryer cavity via the input port; exhaustingsubstantially all of the blown air from the dryer cavity external to thelavatory through the exhaust port comprises: exhausting substantiallyair blown through the exhaust port from the dryer cavity to the ECS. 18.The method of claim 15, wherein: blowing air through the dryer cavityvia the input port comprises: blowing air through the dryer cavity usinga first blower; exhausting substantially all of the blown air from thedryer cavity external to the lavatory through the exhaust portcomprises: drawing substantially all of the blown air from the dryercavity external to the lavatory via a second blower.
 19. The method ofclaim 15, further comprising: directing an antimicrobial substantiallyinto the drying cavity.
 20. An apparatus for drying a hand in alavatory, comprising: means for accepting the hand having moisturethereon in an opening of a dryer cavity having an input port and anexhaust port; means for blowing air through the dryer cavity via theinput port, the blown air removing moisture from the hand accepted intothe opening of the cavity; means for exhausting the blown air from thedryer cavity external to the lavatory through the exhaust port; andmeans for providing the blown air from the exhaust port to the inputport of the dryer cavity via an air channel isolated from an interiorvolume of the lavatory.